Device Having Spare I/O and Method of Using a Device Having Spare I/O

1. A computer system, comprising: a processor having at least W I/O lines; a bus for transferring at least W I/O bits to and from said processor; a memory module attached to said bus, said memory module for storing and saving a W-bit wide word, wherein said W-bit wide word is applied to said bus, wherein said memory module is comprised of a plurality of memory devices having more than W I/O lines, wherein at least one memory device has a spare I/O line that is not connected to said bus, and wherein said at least one memory device includes; said spare I/O line; N–1 I/O lines, wherein N is an integer; N addressable arrays, at least one of which is associated with said spare I/O line; N multiplexers for routing signals from said N–1 I/O lines and from said spare I/O line to said addressable arrays in response to control signals; and a multiplex controller for producing said control signals; wherein data on at least one of said N–1 I/O lines can be stored in and/or read from said array associated with said spare I/O line.

2. A computer according to claim 1 , wherein at least one multiplexer is an N-to-1 multiplexer.

3. A computer according to claim 2 , wherein at least one multiplexer is a 2-to-1 multiplexer.

4. A computer according to claim 3 , wherein at least one multiplexer is a 3-to-1 multiplexer.

5. A computer according to claim 1 , wherein at least one multiplexer can mute signals to an associated array.

6. A computer according to claim 1 , wherein at least one multiplexer shifts signals on an I/O line to an adjacent multiplexer.

7. A memory module for storing and saving a W-bit wide word applied to a bus, comprising: an interface for communicating with the bus; and a plurality of memory devices having more man W I/O lines, wherein at least one memory device has a spare I/O line that is not connected to said bus, and wherein said at least one memory device includes: said spare I/O line; N–1 I/O lines, wherein N is an integer N addressable arrays, at least one of which is associated with said spare I/O line: N multiplexers for routing signals from said N–1 I/O lines and from said spare I/O line to said addressable arrays in response to control signals; and a multiplex controller for producing said control signals; wherein data on at least one of said N–1 I/O line can be stored in and/or read from said array associated with said spare I/O line.

8. A memory module according to claim 7 . wherein, within the at least one memory device: N N-to-1 multiplexers are used; each N-to-1 multiplexer may route data to or from any of the other N-to-1 multiplexers; each N-to-1 multiplexer may route data to or from its associated array; and each N-to-1 multiplexer may apply data to its associated I/O line.

9. A memory module according to claim 7 , wherein, within the at least one memory device: 2 2-to-1 multiplexers and N–2 3-to-1 multiplexers are used: the multiplexers are connected in series with the 3-to-1 multiplexers connected between 2-to-1 multiplexers; each 2-to-1 multiplexer may mute data to or from its neighboring multiplexer; each 3-to-1 multiplexer may mute data to or from any of its neighboring multiplexers; each multiplexer may route data to or from its associated array; and each multiplexer may apply data to its associated I/O line.

10. A memory module according to claim 7 , wherein, within the at least one memory device: one N-to-1 multiplexer and N-1 2-to-1 multiplexers are used: each 24-to-1 multiplexer may mute data to and from the N-to-1 multiplexer; the N-to-1 multiplexer may mute data to and from any 2-to-1 multiplexer; each multiplexer may route data to or from its associated array; and each multiplexer may apply data to its associated I/O line.